x86: Add Intel speedstep and turbo mode code

Intel chips have a turbo mode where they can run faster for a short period
until they reach thermal limits. Add code to adjust and query this feature.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/arch/x86/include/asm/turbo.h b/arch/x86/include/asm/turbo.h
new file mode 100644
index 0000000..bb0d4b4
--- /dev/null
+++ b/arch/x86/include/asm/turbo.h
@@ -0,0 +1,31 @@
+/*
+ * From coreboot file of the same name
+ *
+ * Copyright (C) 2011 The ChromiumOS Authors. All rights reserved.
+ *
+ * SPDX-License-Identifier:	GPL-2.0
+ */
+
+#ifndef _ASM_TURBO_H
+#define _ASM_TURBO_H
+
+#define CPUID_LEAF_PM		6
+#define PM_CAP_TURBO_MODE	(1 << 1)
+
+#define MSR_IA32_MISC_ENABLES	0x1a0
+#define H_MISC_DISABLE_TURBO	(1 << 6)
+
+enum {
+	TURBO_UNKNOWN,
+	TURBO_UNAVAILABLE,
+	TURBO_DISABLED,
+	TURBO_ENABLED,
+};
+
+/* Return current turbo state */
+int turbo_get_state(void);
+
+/* Enable turbo */
+void turbo_enable(void);
+
+#endif